The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
I have holders that will accommodate both left and right handed cutters, you just have to remember to rotate the chuck the right way for the cutter you are using as you mount right handed ones inverted. The holders differ in whether the clamp press the tool up or down.
Not a huge amount of progress recently as I've been tied up with a few other things - example just been making up the latest pork order of 116 kgs of freezer ready pork for customers this afternoon. (Sorry Will-D - that was those two Berkshires!) Also both my workshop PC and Printer decided to die one after the other. PC resurrected but much hassle getting it's Win7 re-authorised having replaced the motherboard, printer sadly terminal and replacement ordered!
However I HAVE actually cut metal with the lathe - not a lot, but just enough to 'set' a couple of tools the old fashioned 'cut and measure' way. The Renishaw HPA Tool Arm is fully working, but so far the only software I've located is a sub-routine that admittedly does most of the work, but the program that calls it is missing.
The Siemens controller is rather convoluted in the way it works. At the high level you have normal G code programs which can call subroutines and / or 'cycles'. Then the Subroutines (which are held in a different bit of memory) can use 'R Parameters' (again in a different bit of memory) as can the 'Cycles' - the cycles (identified with the '@' sign can be very simple functions such as 'jump to location' up to quite complex one such as 'move towards the probe, stop when you hit it, and transfer the X&Z co-ordinates to R parameters'
And just to complicate matters further there are three 'channels' that programs can run in simultaneously - not explored that feature yet :scratch:
In the case of the Tool Probe Tool Offset program, a set of R parameters hold the location of the probe, and it trots off and chooses the tools one by one, reads their roughly set (by ruler +/- 5 mm) position, finds which way the cutting edge faces from a manually set table, and advances the tool into the probe, hopefully then stopping and transferring the accurate co-ordinates into the Tool Table.
At the moment my puzzle is how to accurately measure the static position of the Renishaw HPA Tool Probe. The slightest contact and it's tip of course moves so darn difficult, especially as you are in free space with no reference planes to work from. I suspect that I'm going to have to make up a 'setting tool' with accurately measured offsets done on a surface plate, measure it with the HPA Tool Probe and make corrections to it's stored location until the setting tool measures correctly.
. . . but other things in life get in the way !
awemawson:
For those of you wanting to practise before you apply to Bletchley Park to join the Cryptology course I'm attaching the 'Sub Program' or subroutine that does most of the probing.
A few clues to set you off - these are the meanings of some of the 'cycles' :
@100 = absolute jump
@122 = If / THEN / ELSE jump
@320 = Transfer Tool Offsets to R parameters
@720 = Flying Measurement
. . . simples really :ddb:
awemawson:
Today I got more parcels from Germany :thumbup:
A complete Input Output framework with four i/o cards for the princely sum of £13.43 plus £16.12 postage, and the awaited Measuring Circuit (Basically the card that handles the Encoders, and produces the analogue outputs to the DC servo drive) again for a bargain basement price of £12.98 plus £14.50 postage.
At those prices I really wasn't expecting much, but they came immaculately packed, wrapped in anti-static, AND THEY WORK :clap: No idea why they were so cheap - eBay is full of ones at more than ten times the price.
There are two versions of the Measuring card, a wider one like my original that will take a daughter board, and this version, which apart from the sockets for the extra card and the width of the frame are identical. (I knew that this was the narrow version.)
I plugged it in and tested it and all functions perform just like my original, so it's a good cheap shelf spare, as is the I/O rack. Needless to say the M19 axial positioning issue wasn't affected, but then I didn't expect it to be - I'm more and more certain it's a software 'setting bits' issue
awemawson:
So having totally failed to unscrew some hydraulic fittings this morning I returned to the Beaver for consolation and set too with the Tool Probing Software.
Ploughing through and translating that subroutine / sub-program that I attached above I found several errors where it could not possibly have been able to run - they looked like typos, with variable names being muddled up. Anyway I concentrated on 'Type 3' tools and got the section of code measuring them working. Gosh it must be about the most stressful bit of coding, launching a massive tool turret at a delicate probe and hoping it remembers that it's supposed to stop when it kisses.
I liken testing the program after you've written it to letting your child cross the road for the first time :bugeye:
Anyway Type 3 tools now can be measured, and I need to work on the other types when time permits. The Type 8 tool as per the illustration a/ isn't dealt with in the program, and b/ I haven't a clue how I'm going to do it - X measurement is no problem, but how the heck do you do Z :scratch:
There is a video of it measuring, uploading to Youtube as I type - I'll include it when its cooked!
awemawson:
Here is the Video - Tool Probing Tentatively at very low feed speed !
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